Joey Herren said the 4-alarm fire broke out at 4:12 a.m in the rear of the building, located at 504 Ave. G.

Heavy smoke and flames were seen shooting out of windows and the building's roof. You can watch crews battle the fire as sections of the building collapse in a video, posted by Lisa Shepler, here

. CAUTION: Use of strong language can be heard at the end of the video.

More than 40 firefighters from Ft. Madison, Montrose, West Point and Keokuk fire departments assisted in the fire. Herren said no one was injured. The building was vacant at the time when the fire broke out. Herren said the owners were in St. Louis. They'd used the second story as a storage area.

The State Fire Marshal will be on scene Monday to further investigate the cause of the fire.